Rich, Rich, Sorry I just got to this email. I believe I have a way for you to recover them economically providing that NO COMPONENTS HAVE BEEN LOADED on the reverse side. If this is the case, cut a stainless steel stencil say 6 mils thick for the component pads. Align the stencil to the board pads using a frame which you are going to make cheaply at your local tooling house to hold the loaded board in a nest and hold the stencil frame. Then you are going to use an airbrasive micro blaster loaded with something like coconut shell to remove the oxide. The stencil will mask the board material and so only the solderable areas will get the treatment. You will then clean the assembly thoroughy agitating in DI water, followed immediately by a rinse in IPA which will remove any residual water. Then you are going to assemble them the same day. Have fun Any other method I believe may involve you in field failure which would be far more expensive potentially than scapping the boards If you need any clarification call me please any time after 08-30 AM pacific time on my mobile. 408 515 4992 Kind regards, John -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of JaMi Smith Sent: Wednesday, October 18, 2006 9:04 PM To: [log in to unmask] Subject: Re: [TN] Oxidized PCBs I am going way out on a limb here, so please save the boo's and hiss's. 1. How much assembly is done on the other side? Anything that can be striped off without too much loss and without damage? 2. How much, if any, assembly is done on the affected side? 3. Can you liberally hand flux the problem areas / side with something like good old Kester 1544 Flux and do good scrub with an trimmed down acid brush, and then do a hot air reflow, followed by a good cleaning, and then try and start from scratch with paste on that side? Whatever you do, you are probably going to have to spend some rework money on this to get 170 units done, so the things to ask are what can be saved, and at what cost, and how much rework for each board is needed. You say that you have $600 tied up in each board at present. Where is that money? Is it in a few parts that could be pulled and used on another assembly? Is it in the board? I am looking at this as a "rework" problem, since even though the boards have never been finished, it appears that you are going to have to handle it in the same way. I am assuming that you do not have a rework department of your own, but you might consider setting one up, since the money you will spend on equipment may well be much much less than what you are about to lose. Another solution would be to look into someone who does rework. May just be time to looking into buying something like a "Chipmaster" from A.P.E., or something similar either from them or another vendor, assuming you have a good tech that can operate it. Time is also a big question . . . do you have any? JaMi ----- Original Message ----- From: "Rich Wolbert" <[log in to unmask]> To: <[log in to unmask]> Sent: Wednesday, October 18, 2006 6:31 AM Subject: [TN] Oxidized PCBs > OK, I know you guys are probably going to shake your head on this one, but > I have to ask. We have a double sided fine pitch SMT assembly and we > decided to go to white tin for the pad material. Here's where the problem > comes in, we ran one side and when we started process the other side we > found counterfeit chips. We stopped production for two weeks until the > correct parts came in. When we tried to run the boards again, the PCB's > oxidized so badly over the two weeks that we can not get the solder to > wet. Any suggestions, other than scrapping the 170 assemblies at $600 a > piece? > > --------------------------------------------------- > Technet Mail List provided as a service by IPC using LISTSERV 1.8e > To unsubscribe, send a message to [log in to unmask] with following text in > the BODY (NOT the subject field): SIGNOFF Technet > To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) > To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest > Search the archives of previous posts at: http://listserv.ipc.org/archives > Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 > ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 -----------------------------------------------------